To start with my periods have never been super regular, maybe a week or less late.

However, I am currently 18 days late and I can’t figure out why.

I’m not pregnant, or atleast i’m 99.9% sure that i’m not.

Any input of what could be causing this and how late I should let it get before getting checked out?

I haven’t had any lifestyle changes as far as eating and exercise or weight loss or gain. I don’t think I’m anymore or less stressed than my usual self.